Mingo, the sixth overall pick in the 2013 draft, hasn't been allowed to practice in two weeks. He was injured Aug. 15 in a preseason game against the Detroit Lions and spent 48 hours in the hospital. Two independent doctors not treating Mingo said the risk of returning from the injury before being fully healed is extreme.

Browns head coach Rob Chudzinski hasn't ruled out placing Mingo on the physically unable to perform list, which would idle the pass-rushing specialist for at least six weeks before he could be activated.

"We have no timetable," Chudzinski said.

Mingo's current physical activity is limited to light running workouts.

Recovery time from a bruised lung is difficult to estimate, and doctors said in August Mingo could miss more than one month. Mingo said he will not rush back under the advisement of team doctors.

Without Mingo, the Browns would start Jabaal Sheard at right outside linebacker with Paul Kruger, the newcomer from the Baltimore Ravens who signed a $40 million deal in free agency, on the left side. Depth isn't great at the position, but former Auburn defensive end Quentin Groves, an NFL journeyman who had a bounceback season with the Arizona Cardinals in 2012, is listed as the primary backup. Groves and Kruger had one sack apiece in the first three preseason games.

Sheard led the Browns with seven sacks in 2012, but the Browns transitioned to a 3-4 scheme, pushing the former University of Pittsburgh standout, a second-round pick in 2011, to outside linebacker.

Cleveland ends the exhibition season Thursday against the Chicago Bears.